Add support for links to resources

[tobywf]

Add an e.g. deepLink property to the schema that allows generating links to a resource given identifiers. This is useful for the console.

[tobywf]

Example from EC2 in the deeplink package:

image({ region }) {
  return `/ec2/v2/home?region=${region}#Images:sort=name`
},
instance({ region, resource }) {
  return `/ec2/home?region=${region}#Instances:instanceId=${resource}`;
},

[tobywf]

Proposal for adding this to a schema:

{
   [...]
  "deeplink": {
    "mapping": {
      "instanceId": "#/InstanceId"
    },
    "template": "https://{region}.console.aws.amazon.com/ec2/v2/home?region={region}#Instances:instanceId=${instanceId}"
  }
}

where mapping maps a simple key to a JSON pointer (URI fragment or not?) which can be applied to a resource blob, or empty if not required. global variables like region don't need to be mapped.

Open questions:

• [ ] relative vs absolute URL (think of partner resources)
• [ ] HTTPS only
• [ ] which global vars
• [ ] template syntax
• [ ] JSON pointers are URI fragment representation or vanilla

[johnttompkins]

going to move this to the schema repo for better tracking